Monitoring of air quality

It is important to assess ambient air quality at the intensive monitoring plots for two reasons. Firstly, air pollutants may cause adverse effects to forest trees and forest ecosystems via direct effects, and secondly, the knowledge of pollutant concentrations in the atmosphere will improve estimates of dry deposition to the forest plots. Measurements of air pollution deposition to forest trees are mandatory in the Intensive Monitoring Programme, and a large number of sites measuring throughfall and wet deposition have been established throughout Europe. However, throughfall measurements provide insufficient information to provide reliable estimates of dry deposition of nitrogen compounds, and additional modeling procedures must be carried out. Air pollutants of interest for this purpose are nitrogen dioxide, ammonia and other gaseous and particulate nitrogen species. [...]